剑指offer面试题5：逆序打印单链表(Java)

Java创建单链表(头插法、尾插法)，并逆序打印单链表：

package day_0324;
import java.util.Scanner;
import java.util.Stack;
class ListNode
{
    int val;
    ListNode next;
    public ListNode(int val)
    {
        this.val=val;
    }
}
public class ListNodeTest
{
    public static void main(String[] args)
    {
        //railInsertCreatList(scanner);
        headInsertCreateList();
    }
    /**
     * 头插法建立单链表
     * @param scanner
     */
    private static void headInsertCreateList()
    {
        Scanner scanner=new Scanner(System.in);
        while(scanner.hasNext())
        {
            ListNode head=new ListNode(-1);
            head.next=null;//head为头结点，无意义
            String str=scanner.nextLine();
            String[] temp=str.split(" ");
            for(int i=0;i<temp.length;i++)
            {
                ListNode node=new ListNode(Integer.valueOf(temp[i]));
                node.next=head.next;
                head.next=node;
            }
            ListNode p=head.next;
            while(p!=null)
            {
                System.out.println(p.val);
                p=p.next;
            }
        }
        scanner.close();
    }

    /**
     * 尾插法建立单链表
     * @param scanner
     */
    @SuppressWarnings("unused")
    private static void railInsertCreatList()
    {
        Scanner scanner=new Scanner(System.in);
        while(scanner.hasNext())
        {
            ListNode head=new ListNode(-1);
            head.next=null;
            ListNode r=head;
            String str=scanner.nextLine();
            String[] temp=str.split(" ");
            for(int i=0;i<temp.length;i++)
            {
                ListNode node=new ListNode(Integer.valueOf(temp[i]));
                r.next=node;
                r=node;
            }
            r.next=null;
            ListNode p=head.next;
            while(p!=null)
            {
                System.out.println(p.val);
                p=p.next;
            }
        }
        scanner.close();
    }
    /**
     * 递归方法逆序打印单链表
     * @param head
     */
    public static void printListReverse1(ListNode head)
    {
        if(head!=null)
        {
            if(head.next!=null)
            {
                printListReverse1(head.next);
            }
        }
        System.out.println(head.val);
    }
    /**
     * 使用栈逆序打印单链表
     * @param head
     */
    public static void printListReverse2(ListNode head)
    {
         Stack<Integer> stack=new Stack<Integer>();
        while(head!=null)
        {
            stack.push(head.val);
            head=head.next;
        }
        while(!stack.isEmpty())
        {
            System.out.println(stack.pop());
        }
    }
}